Application of data envelopment analysis to studies of irrigation efficiency in andalusia

The semiarid climate of the majority of agricultural districts in the Mediterranean means that water is a key factor limiting production. It is therefore necessary to distribute water in the most efficient way possible and foment the sustainable use of this valuable resource. It is a difficult task to ascertain whether the use of water in an irrigation district is efficient or not, given that water as a resource cannot be considered in an isolated manner. The development of techniques for data envelopment analysis (DEA) has made it possible to evaluate, in a global manner, where the application of water is most efficient. DEA techniques consider the production process as a set of inputs which obtain a set of outputs in the form of profits. The study of efficiency as a combination of resources allows us to assess when the application of water will lead to greater profitability and hence aid water management authorities in distributing the water of their basins in an appropriate manner. In this study, the data envelopment analysis Baker, Charnes, and Cooper model is applied to all of the irrigation districts in Andalusia (Southern Spain). Using the Wilcoxon-Mann-Withney statistical test we conclude that extensive agriculture (located in the interior) and intensive agriculture (on the littoral) are difficult to compare. Although intensive agriculture with localized irrigation systems achieves the highest efficiency values, the spatial distribution of efficiencies is of great utility in detecting local inefficiencies. It is also useful in providing general guidelines as to which trends should be followed in order to obtain the greatest possible efficiency.